diff --git a/libboard_zynq/src/lib.rs b/libboard_zynq/src/lib.rs
index 5627e0a..b7316f0 100644
--- a/libboard_zynq/src/lib.rs
+++ b/libboard_zynq/src/lib.rs
@@ -17,4 +17,5 @@ pub mod flash;
 pub mod dmac;
 pub mod time;
 pub mod timer;
+pub mod sdio;
 pub mod logger;
diff --git a/libboard_zynq/src/sdio/mod.rs b/libboard_zynq/src/sdio/mod.rs
new file mode 100644
index 0000000..77e8519
--- /dev/null
+++ b/libboard_zynq/src/sdio/mod.rs
@@ -0,0 +1 @@
+mod regs;
\ No newline at end of file
diff --git a/libboard_zynq/src/sdio/regs.rs b/libboard_zynq/src/sdio/regs.rs
new file mode 100644
index 0000000..0cd47cb
--- /dev/null
+++ b/libboard_zynq/src/sdio/regs.rs
@@ -0,0 +1,547 @@
+use volatile_register::{RO, RW, WO};
+
+use libregister::{register, register_at, register_bit, register_bits, register_bits_typed};
+
+#[repr(C)]
+pub struct RegisterBlock {
+    pub sdma_system_address: RW<u32>,
+    pub block_size_block_count: BlockSizeBlockCount,
+    pub argument: RW<u32>,
+    pub transfer_mode_command: TransferModeCommand,
+    pub responses: [RO<u32>; 4],
+    pub buffer: RW<u32>,
+    pub present_state: PresentState,
+    /// Host. power, block gap, wakeup control
+    pub control: Control,
+    /// Clock and timeout control, and software reset register.
+    pub timing_control: TimingControl,
+    pub interrupt_status: InterruptStatus,
+    pub interrupt_status_en: InterruptStatusEn,
+    pub interrupt_signal_en: InterruptSignalEn,
+    pub auto_cmd12_error_status: AutoCmd12ErrorStatus,
+    pub capabilities: Capabilities,
+    pub max_current_capabilities: MaxCurrentCapabilities,
+    pub force_event: ForceEvent,
+    pub adma_error_status: AdmaErrorStatus,
+    pub adma_system_address: RW<u32>,
+    pub boot_data_timeout_counter: RW<u32>,
+    pub debug_selection: DebugSelection,
+    pub spi_interrupt_support: SpiInterruptSupport,
+    pub misc_reg: MiscReg,
+}
+
+#[allow(unused)]
+#[repr(u8)]
+pub enum CommandType {
+    Normal = 0b00,
+    Suspend = 0b01,
+    Resume = 0b10,
+    Abort = 0b11,
+}
+
+#[allow(unused)]
+#[repr(u8)]
+pub enum ResponseTypeSelect {
+    NoResponse = 0b00,
+    Length136 = 0b01,
+    Length48 = 0b10,
+    Legnth48Check = 0b11,
+}
+
+#[allow(unused)]
+#[repr(u8)]
+pub enum BusVoltage {
+    /// 3.3V
+    V33 = 0b111,
+    /// 3.0V, typ.
+    V30 = 0b110,
+    /// 1.8V, typ.
+    V18 = 0b101,
+}
+
+#[allow(unused)]
+#[repr(u8)]
+pub enum DmaSelect {
+    SDMA = 0b00,
+    ADMA1 = 0b01,
+    ADMA2 = 0b10,
+    ADMA3 = 0b11,
+}
+
+#[allow(unused)]
+#[repr(u8)]
+/// SDCLK Frequency divisor, d(number) means baseclock divided by (number).
+pub enum SdclkFreqDivisor {
+    D256 = 0x80,
+    D128 = 0x40,
+    D64 = 0x20,
+    D32 = 0x10,
+    D16 = 0x08,
+    D8 = 0x04,
+    D4 = 0x02,
+    D2 = 0x01,
+    D1 = 0x00,
+}
+
+#[allow(unused)]
+#[repr(u8)]
+pub enum AdmaErrorState {
+    StStop = 0b00,
+    StFds = 0b01,
+    StTfr = 0b11,
+}
+
+#[allow(unused)]
+#[repr(u8)]
+pub enum SpecificationVersion {
+    V1 = 0,
+    V2 = 1,
+}
+
+register_at!(RegisterBlock, 0xE0100000, sd0);
+register_at!(RegisterBlock, 0xE0101000, sd1);
+
+register!(block_size_block_count, BlockSizeBlockCount, RW, u32);
+register_bits!(
+    block_size_block_count,
+    /// Current transfer block count.
+    blocks_count,
+    u16,
+    16,
+    31
+);
+register_bits!(
+    block_size_block_count,
+    /// Host SDMA Buffer Size, size = 2^(val + 2) KB.
+    dma_buffer_size,
+    u8,
+    12,
+    14
+);
+register_bits!(
+    block_size_block_count,
+    /// Block size for data transfer. Unit: byte.
+    transfer_block_size,
+    u16,
+    0,
+    11
+);
+
+register!(transfer_mode_command, TransferModeCommand, RW, u32);
+register_bits!(
+    transfer_mode_command,
+    /// Command Number.
+    command_index,
+    u8,
+    24,
+    29
+);
+register_bits_typed!(
+    transfer_mode_command,
+    /// Command type register.
+    command_type,
+    u8,
+    CommandType,
+    22,
+    23
+);
+register_bit!(
+    transfer_mode_command,
+    /// 1 if data is present and shall be transferred using the DAT line.
+    data_present_select,
+    21
+);
+register_bit!(
+    transfer_mode_command,
+    /// If the index field shall be checked.
+    index_check_en,
+    20
+);
+register_bit!(
+    transfer_mode_command,
+    /// If CRC shall be checked.
+    crc_check_en,
+    19
+);
+register_bits_typed!(
+    transfer_mode_command,
+    /// Different type of response.
+    response_type_select,
+    u8,
+    ResponseTypeSelect,
+    16,
+    17
+);
+register_bit!(
+    transfer_mode_command,
+    /// Enables the multi block DAT line data transfer.
+    multi_block_en,
+    5
+);
+register_bit!(
+    transfer_mode_command,
+    /// 1 if read (card to host), 0 if write (host to card).
+    direction_select,
+    4
+);
+register_bit!(
+    transfer_mode_command,
+    /// If CMD12 shall be issued automatically when last block transfer is completed.
+    auto_cmd12_en,
+    2
+);
+register_bit!(
+    transfer_mode_command,
+    /// Enable the block count register.
+    block_count_en,
+    1
+);
+register_bit!(
+    transfer_mode_command,
+    /// Enable DMA,
+    dma_en,
+    0
+);
+
+register!(present_state, PresentState, RO, u32);
+register_bit!(
+    present_state,
+    /// CMD Line Signal Level.
+    cmd_line_level,
+    24
+);
+register_bit!(
+    present_state,
+    /// Signal level in DAT[3]
+    dat3_level,
+    23
+);
+register_bit!(
+    present_state,
+    /// Signal level in DAT[2]
+    dat2_level,
+    22
+);
+register_bit!(
+    present_state,
+    /// Signal level in DAT[1]
+    dat1_level,
+    21
+);
+register_bit!(
+    present_state,
+    /// Signal level in DAT[0]
+    dat0_level,
+    20
+);
+register_bit!(
+    present_state,
+    /// Write enabled and inverse of SDx_WP pin level.
+    write_enabled,
+    19
+);
+register_bit!(
+    present_state,
+    /// Card detected and inverse of SDx_CDn pin level.
+    card_detected,
+    18
+);
+register_bit!(present_state, card_state_stable, 17);
+register_bit!(present_state, card_inserted, 16);
+register_bit!(present_state, buffer_read_en, 11);
+register_bit!(present_state, buffer_write_en, 10);
+register_bit!(present_state, read_transfer_active, 9);
+register_bit!(present_state, write_transfer_active, 8);
+register_bit!(present_state, dat_line_active, 2);
+register_bit!(present_state, command_inhibit_dat, 1);
+register_bit!(present_state, command_inhibit_cmd, 0);
+
+register!(control, Control, RW, u32);
+register_bit!(
+    control,
+    /// Enable wakeup event via SD card removal assertion.
+    wakeup_on_removal,
+    26
+);
+register_bit!(
+    control,
+    /// Enable wakeup event via SD card insertion assertion.
+    wakeup_on_insertion,
+    25
+);
+register_bit!(
+    control,
+    /// Enable wakeup event via card interrupt assertion.
+    wakeup_on_interrupt,
+    24
+);
+register_bit!(
+    control,
+    ///Enable interrupt detection at the block gap for a multiple block transfer.
+    interrupt_at_block_gap,
+    19
+);
+register_bit!(
+    control,
+    /// Enable the use of the read wait protocol.
+    read_wait_control,
+    18
+);
+register_bit!(
+    control,
+    /// Restart a trasaction which was stopped using the stop at block gap request.
+    continue_req,
+    17
+);
+register_bit!(
+    control,
+    /// Stop executing a transaction at the next block gap.
+    stop_at_block_gap_req,
+    16
+);
+register_bits_typed!(control, bus_voltage, u8, BusVoltage, 9, 11);
+register_bit!(control, bus_power, 8);
+register_bit!(
+    control,
+    /// Selects source for card detection. 0 for SDCD#, 1 for card detect test level.
+    card_detect_signal,
+    7
+);
+register_bit!(
+    control,
+    /// Indicates card inserted or not. Enabled when card detect signal is 1.
+    card_detect_test_level,
+    6
+);
+register_bits_typed!(control, dma_select, u8, DmaSelect, 3, 4);
+register_bit!(control, high_speed_en, 2);
+register_bit!(
+    control,
+    /// Select the data width of the HC. 1 for 4-bit, 0 for 1-bit.
+    data_width_select,
+    1
+);
+register_bit!(
+    control,
+    /// 1 for LED on, 0 for LED off.
+    led_control,
+    0
+);
+
+register!(timing_control, TimingControl, RW, u32);
+register_bit!(
+    timing_control,
+    /// Software reset for DAT line.
+    software_reset_dat,
+    26
+);
+register_bit!(
+    timing_control,
+    /// Software reset for CMD line.
+    software_reset_cmd,
+    25
+);
+register_bit!(
+    timing_control,
+    /// Software reset for ALL.
+    software_reset_all,
+    24
+);
+register_bits!(
+    timing_control,
+    /// Determines the interval by which DAT line time-outs are detected.
+    /// Interval = TMCLK * 2^(13 + val)
+    /// Note: 0b1111 is reserved.
+    timeout_counter_value,
+    u8,
+    16,
+    19
+);
+register_bits_typed!(
+    timing_control,
+    /// Selects the frequency divisor, thus the clock frequency for SDCLK.
+    /// Choose the smallest possible divisor which results in a clock frequency
+    /// that is less than or equal to the target frequency.
+    sdclk_freq_divisor,
+    u8,
+    SdclkFreqDivisor,
+    8,
+    15
+);
+register_bit!(timing_control, sd_clk_en, 2);
+register_bit!(
+    timing_control,
+    /// 1 when SD clock is stable.
+    /// Note that this field is read-only.
+    internal_clk_stable,
+    1,
+    RO
+);
+register_bit!(timing_control, internal_clk_en, 0);
+
+register!(interrupt_status, InterruptStatus, RW, u32, 1 << 15 | 1 << 8);
+register_bit!(interrupt_status, ceata_error, 29, WTC);
+register_bit!(interrupt_status, target_response_error, 28, WTC);
+register_bit!(interrupt_status, adma_error, 25, WTC);
+register_bit!(interrupt_status, auto_cmd12_error, 24, WTC);
+register_bit!(interrupt_status, current_limit_error, 23, WTC);
+register_bit!(interrupt_status, data_end_bit_error, 22, WTC);
+register_bit!(interrupt_status, data_crc_error, 21, WTC);
+register_bit!(interrupt_status, data_timeout_error, 20, WTC);
+register_bit!(interrupt_status, command_index_error, 19, WTC);
+register_bit!(interrupt_status, command_end_bit_error, 18, WTC);
+register_bit!(interrupt_status, command_crc_error, 17, WTC);
+register_bit!(interrupt_status, command_timeout_error, 16, WTC);
+register_bit!(interrupt_status, error_interrupt, 15, RO);
+register_bit!(interrupt_status, boot_terminate_interrupt, 10, WTC);
+register_bit!(interrupt_status, boot_ack_rcv, 9, WTC);
+register_bit!(interrupt_status, card_interrupt, 8, RO);
+register_bit!(interrupt_status, card_removal, 7, WTC);
+register_bit!(interrupt_status, card_insertion, 6, WTC);
+register_bit!(interrupt_status, buffer_read_ready, 5, WTC);
+register_bit!(interrupt_status, buffer_write_ready, 4, WTC);
+register_bit!(interrupt_status, dma_interrupt, 3, WTC);
+register_bit!(interrupt_status, block_gap_event, 2, WTC);
+register_bit!(interrupt_status, transfer_complete, 1, WTC);
+register_bit!(interrupt_status, command_complete, 0, WTC);
+
+register!(interrupt_status_en, InterruptStatusEn, RW, u32);
+register_bit!(interrupt_status_en, ceata_error_status_en, 29);
+register_bit!(interrupt_status_en, target_response_error_status_en, 28);
+register_bit!(interrupt_status_en, adma_error_status_en, 25);
+register_bit!(interrupt_status_en, auto_cmd12_error_status_en, 24);
+register_bit!(interrupt_status_en, current_limit_error_status_en, 23);
+register_bit!(interrupt_status_en, data_end_bit_error_status_en, 22);
+register_bit!(interrupt_status_en, data_crc_error_status_en, 21);
+register_bit!(interrupt_status_en, data_timeout_error_status_en, 20);
+register_bit!(interrupt_status_en, cmd_index_error_status_en, 19);
+register_bit!(interrupt_status_en, cmd_end_bit_error_status_en, 18);
+register_bit!(interrupt_status_en, cmd_crc_error_status_en, 17);
+register_bit!(interrupt_status_en, cmd_timeout_error_status_en, 16);
+register_bit!(interrupt_status_en, fixed_to_0, 15, RO);
+register_bit!(interrupt_status_en, boot_terminate_interrupt_en, 10);
+register_bit!(interrupt_status_en, boot_ack_rcv_en, 9);
+register_bit!(interrupt_status_en, card_interrupt_status_en, 8);
+register_bit!(interrupt_status_en, card_removal_status_en, 7);
+register_bit!(interrupt_status_en, card_insertion_status_en, 6);
+register_bit!(interrupt_status_en, buffer_read_ready_status_en, 5);
+register_bit!(interrupt_status_en, buffer_write_ready_status_en, 4);
+register_bit!(interrupt_status_en, dma_interrupt_status_en, 3);
+register_bit!(interrupt_status_en, block_gap_evt_status_en, 2);
+register_bit!(interrupt_status_en, transfer_complete_status_en, 1);
+register_bit!(interrupt_status_en, cmd_complete_status_en, 0);
+
+register!(interrupt_signal_en, InterruptSignalEn, RW, u32);
+register_bit!(interrupt_signal_en, ceata_error_signal_en, 29);
+register_bit!(interrupt_signal_en, target_response_error_signal_en, 28);
+register_bit!(interrupt_signal_en, adma_error_signal_en, 25);
+register_bit!(interrupt_signal_en, auto_cmd12_error_signal_en, 24);
+register_bit!(interrupt_signal_en, current_limit_error_signal_en, 23);
+register_bit!(interrupt_signal_en, data_end_bit_error_signal_en, 22);
+register_bit!(interrupt_signal_en, data_crc_error_signal_en, 21);
+register_bit!(interrupt_signal_en, data_timeout_error_signal_en, 20);
+register_bit!(interrupt_signal_en, cmd_index_error_signal_en, 19);
+register_bit!(interrupt_signal_en, cmd_end_bit_error_signal_en, 18);
+register_bit!(interrupt_signal_en, cmd_crc_error_signal_en, 17);
+register_bit!(interrupt_signal_en, cmd_timeout_error_signal_en, 16);
+register_bit!(interrupt_signal_en, fixed_to_0, 15, RO);
+register_bit!(interrupt_signal_en, boot_terminate_interrupt_signal_en, 10);
+register_bit!(interrupt_signal_en, boot_ack_rcv_signal_en, 9);
+register_bit!(interrupt_signal_en, card_interrupt_signal_en, 8);
+register_bit!(interrupt_signal_en, card_removal_signal_en, 7);
+register_bit!(interrupt_signal_en, card_insertion_signal_en, 6);
+register_bit!(interrupt_signal_en, buffer_read_ready_signal_en, 5);
+register_bit!(interrupt_signal_en, buffer_write_ready_signal_en, 4);
+register_bit!(interrupt_signal_en, dma_interrupt_signal_en, 3);
+register_bit!(interrupt_signal_en, block_gap_evt_signal_en, 2);
+register_bit!(interrupt_signal_en, transfer_complete_signal_en, 1);
+register_bit!(interrupt_signal_en, cmd_complete_signal_en, 0);
+
+register!(auto_cmd12_error_status, AutoCmd12ErrorStatus, RO, u32);
+register_bit!(
+    auto_cmd12_error_status,
+    cmd_not_issued_by_auto_cmd12_error,
+    7
+);
+register_bit!(auto_cmd12_error_status, index_error, 4);
+register_bit!(auto_cmd12_error_status, end_bit_error, 3);
+register_bit!(auto_cmd12_error_status, crc_error, 2);
+register_bit!(auto_cmd12_error_status, timeout_error, 1);
+register_bit!(auto_cmd12_error_status, not_executed, 0);
+
+register!(capabilities, Capabilities, RO, u32);
+register_bit!(capabilities, spi_block_mode, 30);
+register_bit!(capabilities, spi_mode, 29);
+register_bit!(capabilities, support_64bit, 28);
+register_bit!(capabilities, interrupt_mode, 27);
+register_bit!(capabilities, voltage_1_8, 26);
+register_bit!(capabilities, voltage_3_0, 25);
+register_bit!(capabilities, voltage_3_3, 24);
+register_bit!(capabilities, suspend_resume, 23);
+register_bit!(capabilities, sdma, 22);
+register_bit!(capabilities, hgih_speed, 21);
+register_bit!(capabilities, adma2, 19);
+register_bit!(capabilities, extended_media_bus, 18);
+register_bits!(
+    capabilities,
+    /// Length = 2^(9 + v) bytes.
+    max_block_len,
+    u8,
+    16,
+    17
+);
+register_bit!(capabilities, timeout_clock_unit, 7);
+
+register!(max_current_capabilities, MaxCurrentCapabilities, RO, u32);
+register_bits!(max_current_capabilities, max_current_1_8v, u8, 16, 23);
+register_bits!(max_current_capabilities, max_current_3_0v, u8, 8, 15);
+register_bits!(max_current_capabilities, max_current_3_3v, u8, 0, 7);
+
+register!(force_event, ForceEvent, WO, u32);
+register_bit!(force_event, ceata_error, 29);
+register_bit!(force_event, target_response_error, 28);
+register_bit!(force_event, adma_error, 25);
+register_bit!(force_event, auto_cmd12_error, 24);
+register_bit!(force_event, current_limit_error, 23);
+register_bit!(force_event, data_end_bit_error, 22);
+register_bit!(force_event, data_crc_error, 21);
+register_bit!(force_event, data_timeout_error, 20);
+register_bit!(force_event, cmd_index_error, 19);
+register_bit!(force_event, cmd_end_bit_error, 18);
+register_bit!(force_event, cmd_crc_error, 17);
+register_bit!(force_event, cmd_timeout_error, 16);
+register_bit!(force_event, cmd_not_issued_by_auto_cmd12_error, 7);
+register_bit!(force_event, auto_cmd12_index_error, 4);
+register_bit!(force_event, auto_cmd12_end_bit_error, 3);
+register_bit!(force_event, auto_cmd12_crc_error, 2);
+register_bit!(force_event, auto_cmd12_timeout_error, 1);
+register_bit!(force_event, auto_cmd12_not_executed, 0);
+
+register!(adma_error_status, AdmaErrorStatus, RW, u32, 0b11);
+register_bit!(adma_error_status, length_mismatch_error, 2, WTC);
+register_bits_typed!(adma_error_status, error_state, u8, AdmaErrorState, 0, 1);
+
+register!(debug_selection, DebugSelection, WO, u32);
+register_bit!(debug_selection, debug_select, 0);
+
+register!(spi_interrupt_support, SpiInterruptSupport, RW, u32);
+register_bits!(
+    spi_interrupt_support,
+    /// There should be a problem with the documentation of this field.
+    spi_int_support,
+    u8,
+    0,
+    7
+);
+
+register!(misc_reg, MiscReg, RO, u32);
+register_bits!(misc_reg, vendor_version_num, u8, 24, 31);
+register_bits_typed!(misc_reg, spec_ver, u8, SpecificationVersion, 16, 23);
+register_bits!(
+    misc_reg,
+    /// Logical OR of interrupt signal and wakeup signal for each slot.
+    slot_interrupt_signal,
+    u8,
+    0,
+    7
+);
diff --git a/libregister/src/lib.rs b/libregister/src/lib.rs
index 603507b..56696db 100644
--- a/libregister/src/lib.rs
+++ b/libregister/src/lib.rs
@@ -100,6 +100,19 @@ macro_rules! register_rw {
             }
         }
     );
+    ($mod_name: ident, $struct_name: ident, $mask: expr) => (
+        impl libregister::RegisterRW for $struct_name {
+            #[inline]
+            fn modify<F: FnOnce(Self::R, Self::W) -> Self::W>(&mut self, f: F) {
+                unsafe {
+                    self.inner.modify(|inner| {
+                        f($mod_name::Read { inner }, $mod_name::Write { inner: inner & ($mask) })
+                            .inner
+                    });
+                }
+            }
+        }
+    );
 }
 
 #[doc(hidden)]
@@ -168,6 +181,14 @@ macro_rules! register {
         libregister::register_common!($mod_name, $struct_name, VolatileCell<$inner>, $inner);
         libregister::register_vcell!($mod_name, $struct_name);
     );
+
+    // Define read-write register with mask on write (for WTC mixed access.)
+    ($mod_name: ident, $struct_name: ident, RW, $inner: ty, $mask: expr) => (
+        libregister::register_common!($mod_name, $struct_name, volatile_register::RW<$inner>, $inner);
+        libregister::register_r!($mod_name, $struct_name);
+        libregister::register_w!($mod_name, $struct_name);
+        libregister::register_rw!($mod_name, $struct_name, $mask);
+    );
 }
 
 /// Define a 1-bit field of a register
@@ -197,6 +218,47 @@ macro_rules! register_bit {
             }
         }
     );
+
+    // Single bit read-only
+    ($mod_name: ident, $(#[$outer:meta])* $name: ident, $bit: expr, RO) => (
+        $(#[$outer])*
+        impl $mod_name::Read {
+            #[allow(unused)]
+            #[inline]
+            pub fn $name(&self) -> bool {
+                use bit_field::BitField;
+
+                self.inner.get_bit($bit)
+            }
+        }
+    );
+
+    // Single bit write to clear. Note that this must be used with WTC register.
+    ($mod_name: ident, $(#[$outer:meta])* $name: ident, $bit: expr, WTC) => (
+        $(#[$outer])*
+        impl $mod_name::Read {
+            #[allow(unused)]
+            #[inline]
+            pub fn $name(&self) -> bool {
+                use bit_field::BitField;
+
+                self.inner.get_bit($bit)
+            }
+        }
+
+        $(#[$outer])*
+        impl $mod_name::Write {
+            /// Clear bit field. (WTC)
+            #[allow(unused)]
+            #[inline]
+            pub fn $name(mut self) -> Self {
+                use bit_field::BitField;
+
+                self.inner.set_bit($bit, true);
+                self
+            }
+        }
+    );
 }
 
 /// Define a multi-bit field of a register